NO308039B1 - Polybutene-1 resin mixture - Google Patents

Abstract

1. A polybutene-1 resin composition substantially comprising (A) 60 to 95 weight parts of a polybutene-1 resin (A) having (i) a melt flow rate of 0.01 to 5 g/10 min, (ii) the ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 6 or less, and (iii) an isotactic value of 93 % or more, and (B) 40 to 5 weight parts of a polybutene-1 resin (B) having (i) a 20 times or more as large melt flow rate as that of the polybutene-1 resin (A), (ii) the ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)of 6 or less, and (iii) an isotactic value of 93 % or more. i

Description

The present invention relates, as stated in claim 1's preamble, to a polybutene-1-resin mixture, and more particularly to a polybutene-1-resin mixture with excellent impact resistance, creep resistance.

In the past, pipe materials made from a metal such as lead-coated steel pipes, copper pipes and lead pipes have been used as pipe materials for water supply and hot water supply. However, problems do occur, for example there is a risk that for steel pipes "red water" or "black water" may be generated as a result of rust, or in the case of copper pipes "pinholes" may occur and "blue water" may form as a result of electrolytic corrosion, and a pipe material that is not affected by these problems is therefore sought. Thus, pipe materials comprising a synthetic resin such as polyvinyl chloride, polyethylene or polybutene-1 are already used, where there is no risk of rust or "pinholes" forming as a result of electrolytic corrosion.

Of these pipe materials made from synthetic resin, the pipe material comprising polybutene-l resin is one of the most suitable pipe materials for water supply and hot water supply as the polybutene-1 resin has excellent pressure resistance, creep resistance at high temperature, heat resistance and impact strength at low temperature, abrasion resistance and little flexibility. It is thus expected that in the future there will be an increased demand for pipes comprising this polybutene-l-resin.

In European patent publication 0172961A1 a polybutene is shown

1 suitable as material for pipes. The known polybutene-1 contains 0-1 mol% of an olefin with 2-20 carbon atoms different from butene-1 and has

(1) a limiting viscosity in the range 1.5 -

4.0 dl/g measured in decalin at 135°C,

(2) a molecular weight distribution, expressed as the ratio of its weight average molecular weight (Mw) to its number average molecular weight (Mn), of no more than 6, and (3) an isotacticity of at least 95% by weight.

However, although the currently available polybutene-1 resins have excellent stiffness, creep properties, impact resistance strength, crystallization rate, and the like. then they have a narrow molecular weight distribution so that the ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) is 5 or less. Therefore, when such a resin is molded into a pipe with a diameter of 30 mm or less, it can be effectively molded at a low molding speed (3 m/min. or less), but when it is molded into a pipe at a high molding speed, rue occurs surfaces on the inner and outer surface of the tube obtained, and it is thus not possible to obtain tubes with a satisfactory appearance, and there is thus a problem with regard to high casting speed.

It is thus an aim of the invention to provide a polybutene-1 resin mixture which has properties that are actually possessed by a polybutene-1 resin such as excellent stiffness, creep properties and impact resistance strength, and which at the same time has excellent castability, especially castability at high casting speed , so-called high-speed castability.

It has been found that the above purposes and advantages can be achieved with a polybutene-1-resin mixture which is characterized by what is stated in the characterizing part of claim 1. In what follows, this resin mixture is sometimes abbreviated to "polybutene-1-resin mixture-1".

Further features appear from requirements 2 - 9.

According to the invention, there is also provided a polybutene-1-resin mixture (hereafter sometimes abbreviated to "polybutene-1-resin mixture-II"), essentially consisting of (1) 100 parts by weight of the above-mentioned butene-1- resin composition-1, (2) 0.01 to 2 parts by weight of a nucleating agent, and (3) 0-20 parts by weight of a thermoplastic polymer other than a polybutene-1 resin.

The polybutene-1 resin mixture according to the invention will be described in more detail below.

The polybutene-1 resin (A) is the main component in the resin mixture according to the invention, and is a homopolymer of butene-1 or a copolymer of butene-1 with another oz-olefin with 2-20 carbon atoms. In the case of the copolymer, the ratio of the second α-olefin to be copolymerized is 20 mol% or less, preferably 10 mol% or less, and more preferably 5 mol% or less. Examples of another oz-olefin which can be copolymerized include ethylene, propylene, hexene, 4-methylpentene-1, octene-1, decene-1, octadecene-1, etc.

The melt flow rate (MRF(E): ASTM D1238, E) of polybutene-1) resin (A) is 0.01 - 5 g/10 min., preferably 0.1 - 2 g/10 min., and this range provides good extruder castability of the resulting mixture.

Furthermore, in this polybutene-l-resin (A), the ratio is

(Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), which represents the molecular weight distribution, 6 or less, and one resin with a ratio of 5 or less is preferred in view of the resulting mixture then gets an excellent impact resistance.

The weight average molecular weight (Hw), the number average molecular weight (Hn) and the ratio (Hw/Hn) are measured using the following method.

Determination of weight average molecular weight ( Hw ) and number average molecular weight ( Hn ) (a) Using polystyrene of known molecular weight (monodisperse polystyrene, manufactured by TOYA SODA MANUFACTURING CO., LTD.), polystyrenes of different molecular weight were subjected to GPC (gel permeability chromatography) analysis under the following measurement conditions:

Apparatus: "Model 1 150 C", manufactured by Water Co.

Column: "TSKGMH-6", diameter 6 mm, length 600 mm

manufactured by TOYO SODA MANUFACTURING CO., LTD.

Sample quantity: 400 pl

Temperature: 13 5 *C

Flow rate: 1 ml/min.,

and a calibration curve was prepared showing the molecular weight M and the EV (elution volume) value.

(b) Preparation of a sample

A polymer sample whose molecular weight is to be determined and a solvent o-dichlorobenzene is introduced into a bottle to give a solution containing the solvent in an amount of 20 ml per 15 mg of the polymer.

2,6-di-t-butyl-cresol was added as a stabilizer to the polymer solution so that the concentration was 0.1% by weight.

The resulting solution was heated to 140°C i

1 hour and then stirred for 1 hour to completely dissolve the polymer and stabilizer.

Then the solution was filtered at a temperature in the range of 135 to 14CPC using a 0.5 µm filter.

The filtrate was subjected to GPL analysis under the same measurement conditions as given under (a) above,

the number average molecular weight

Hn - EMiNi/ ENi

and the weight average molecular weight

Hw = EMi<2>Ni/ EMiNi

is determined according to the calibration curve prepared above using resulting EV values, and (Hw/Hn) is calculated.

Further, the isotactic value of the polybutene-1 resin (A) is 93% or more, preferably 93-98% because the stiffness, heat resistance and creep resistance of the obtained mixture are then excellent.

Determination of the isotactic value ( II)

The isotactic value (II) was measured according to the following procedure. 1 g of polybutene-1 resin was dissolved in 100 ml of n-decane, and the solution cooled to 0<*>C and allowed to stand at this temperature for 24 hours to precipitate the highly stereoregular component, and % by weight of the insoluble part in relation to all of the resin was designated as the isotactic value II.

The polybutene-1-resin (B), the second main component in the mixture according to the invention is like the polybutene-1-resin

(A) , a homopolymer of butene-1, or a copolymer of butene-1 with another o-olefin of 2-20 carbon atoms, and when

this second oc-olefin with 2-20 carbon atoms is present is

its type and content the same as described for the polybutene-1 resin (A).

In order to achieve good extrusion moldability of the resulting mixture, the melt flow rate (MFR(W): ASTM D 1238, E) of this polybutene-1 resin (B) is 20 times or more, preferably 50-100 times that of melt -the flow rate density of the polybutene-1 resin (A).

Further, in the polybutene-1 resin (B), the ratio (Hw/Hn) of the weight average molecular weight (Hw) to the number average molecular weight (Hn), which represents molecular weight distribution, is 6 or less, and one resin having this ratio of 5 or less is preferred from the point of view that the impact resistance of the resulting mixture is then excellent.

Furthermore, the isotactic value (II) of this polybutene-1-resin (B) is 93% or more, and preferably 93-98% from the consideration that the resulting mixture then obtains excellent stiffness, heat resistance and creep resistance.

In the resin mixture according to the invention, the melting stress for the molten blow blank of the obtained resin mixture will rise and thus the castability and workability will be good, and it will be possible to cast the mixture into a tube at high speed. Furthermore, from the point of view that molded articles with good impact strength are to be obtained, the weight mixing ratios for polybutene-1 resin (A)/polybutene-1 resin (B) are in the range 60:40 to 95:5, preferably 90:10 to 70 :30.

Furthermore, it is preferred that the resin mixture according to the invention further contains a nucleating agent in addition to the polybutene-1 resins (A) and (B), because the solidification rate of the molten resin extruded from the die during pipe casting becomes faster and a more stabilized high-speed castability is obtained, as the speed of the crystal transition, which is special for polybutene-l resins, is promoted even after solidification, and an effect of improved stiffness is further achieved.

Examples of such nucleating agents are polyethylene resins, polyethylene waxes, ethylene bisstearoamide, polypropylene resins, etc. Preferably, the nucleating agent is a polyolefin with a crystallization temperature higher than that of the polybutene-1 resins (A) or (B).

When the nucleating agent is mixed into the resin mixture according to the present invention, the mixing ratio is in the range of 0.01-2 parts by weight, preferably 0.05-0.5 parts by weight per 100 parts by weight in total of the polybutene-1 resin (A) and the polybutene-1 resin (B).

<y>furthermore, it is also possible to mix a thermoplastic polymer other than a polybutene-1 resin into the present mixture in order to improve the impact resistance or other physical properties. Examples of such thermoplastic polymers include olefin elastomers such as ethylene-propylene copolymer resins, polyethylene, polypropylene, poly(4-methylpentene-1), polyisobutylene, etc. When such thermoplastic polymers are mixed, the mixing ratio is 20 parts by weight or less, preferably 15 parts by weight or less per 100 parts by weight of the total amount of the polybutene-1 resin (A) and the polybutene-1 resin (B). In particular, it is preferred to incorporate the olefin elastomer to improve impact resistance.

Furthermore, in order to enhance long-term resistance such as heat aging resistance and resistance to chlorinated water for the molded articles obtained by means of the present resin mixture, the mixture may contain various stabilizers, especially an antioxidant.

Examples of antioxidants include phenol and phosphorus series antioxidants, for example 2,6-di-t-butyl-4-hydroxybenzoate, n-hexadecyl 3,5-di-t-butyl-4-hydroxybenzoate, 1,3,5- trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxy-benzyl)benzene, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6- dimethyl-phenyl)isocyanurate, tris(3,5-di-t-butyl-4-hydroxyphenyl)-isocyanurate, n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate, nickel salt of bis (3,5-d-t-butyl-4-hydroxy-benzoyl-phosphonic acid) monoethyl ester, 2,2'-dihydroxy-3,

31-diffletylcyclohexyl)-5,5'-dimethyl-diphenylmethane, 4,4-thio-bis(3-methyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5 -t-butylphenyl)butane, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, 2,6-di-t-butyl-p-cresol,

4,4'-methylene-bis(2,6-di-t-butyl-phenol), tris(2,4-di-t-butyl-phenyl)phosphite and vitamin E. These can be used alone or in combination with two or more.

When an antioxidant is present, the content will usually be in the range of 0.1-2 parts by weight, preferably in the range of 0.5-1.8 parts by weight per 100 parts by weight of the total weight of the polybutene-1 resin (A) and the polybutene-1 resin (B).

The resin mixture according to the invention can further contain, if necessary, a UV absorber, a fungicide, a rust inhibitor, a lubricant, a filler, a pigment, a heat stabilizer, etc.

The resin mixture according to the invention can be produced according to a method which comprises heat mixing the polybutene-1 resin (A), the polybutene-1 resin (B) and, if necessary, the nucleating agent, the thermoplastic polymer etc. in the mixing conditions given above using a "Henschel mixer", a V-mixer, a belt mixer, a drum mixer, etc., or a method comprising, after the above-mentioned mixing, melt kneading of the mixture using a uniaxial extruder, a multiaxial extruder, "Banburg" mixer, kneader, etc., and then granulate or pulverize the kneaded ingredients. Furthermore, the present mixture can also be prepared by obtaining the polybutene-1 resins (A) and (B) separately by polymerization and then mixing the obtained polymerization solutions by stirring.

For reasons of castability and workability, it is preferred that the resin mixture according to the invention usually has a melt flow rate of 0.2-5 g/10 min., preferably 0.3-3 g/10 min..

Example

In what follows, the invention will be described more specifically with reference to examples and comparative examples.

In the following examples and comparative examples, determination of heat resistance, tensile yield strength and impact strength of pressed sheets of the resin mixture and evaluation of the internal pressure resistance of the resin mixture and castability of a pipe were carried out according to the methods described below.

Heat resistance

Heat resistance was determined according to JIS 7206 ("Vicut" softening temperature test method for thermoplastic resins). This "Vicut" softening temperature is a scale that indicates the maximum usable temperature for a resin, and, in the case of pipes for hot water supply and water supply, it is preferably 100<*>C or more as they occasionally come into contact with hot water.

Flow clean during the tensile test

This was determined according to ASTM D638 using an ASTM Type IV tensile rod.

Supportive strength

This property was determined according to ASTM D256 at 0<*>C using an incision.

Internal pressure resistance

Furthermore, pipes having an inner diameter of 13 mm and an outer diameter of 17 mm were produced using a pipe molding apparatus (manufactured by Hitachi Zosen Sangyo Co., Ltd.) using pellets of each of the polybutene-1 resin mixtures , and evaluated with regard to internal pressure resistance and castability of the pipes according to the following methods.

A tube was immersed in a water bath with a constant temperature adjusted to 90 ± 1°C. Water of 90°C was introduced into the pipe and pressurized so that tension was generated around the pipe to 70kg/cm<2>, and the time before the pipe burst was determined.

Castability of pipes

Tubes were cast at a casting speed of 10 m/min, and the inner and outer surfaces of the resulting tubes were visually observed and evaluated according to the following three criteria.

The castability was good and the appearance of the pipe was

also good.

A..... Molding was possible, but small uneven rough surfaces were formed on the inner and outer surfaces of the tube.

X Pipe casting was not possible.

Reference model A

<Preparation of Titanium Catalyst Component (A)>

4.76 g (50 mmol) of anhydrous magnesium chloride, 25 ml of decane and 23.4 ml (150 mmol) of 2-ethylhexyl alcohol were reacted under heating at 130<*>C for 2 hours to give a uniform solution. 1.11 g (7.5 mmol) of phthalic anhydride was added to the solution, and the mixture was stirred at 130<*>C for an additional 1 hour to dissolve the phthalic anhydride in the uniform solution. The uniform solution thus obtained was cooled to room temperature and the entire solution was then added dropwise over 1 hour to 200 ml (1.8 mol) of titanium tetrachloride kept at -20°C. After complete addition, the temperature of the mixture was raised to 110°C over 4 hours, and when 110°C was reached, 268 mL (12.5 mmol) of diisobutyl phthalate was added and the mixture was kept at said temperature for 2 hours with stirring. After 2 hours of reaction, the solid part was collected by hot filtration, resuspended in 200 ml of TiCl4 and again subjected to reaction with stirring at 110° C. for 2 hours. After complete reaction, the solid part was again collected by hot filtration and washed sufficiently with decane and hexane each at 110°C until no free titanium compounds could be detected in the washings. The titanium catalyst component (A) prepared as above was kept as a slurry in hexane. A portion of the slurry was dried in order to examine the catalyst The composition of the thus obtained titanium catalyst component (A) was 3.1% by weight titanium, 56.0% by weight chloride, 17.0% by weight magnesium and 20.9% by weight diisobutyl phthalate.

<Polymerization>

50 l/hour of hexane, 50 l/hour of liquid butene-1, 0.6 mM/hour of the titanium catalyst (A) prepared above, 100 mM/hour of triisobutylaluminium, 5 mM /hour cyclohexylmethyldimethoxysilane and hydrogen. The hydrogen was fed in so that the mole ratio hydrogen/butene-1 of the gaseous phase part of the reactor was 0.01. The polymerization temperature was maintained at 60°C and the polymerization pressure was 4.7 bar. While the level in the polymerization apparatus was maintained at 100 1, the contents were continuously drawn off. 1 l/hr methanol was added to the polymerization solution, butene-1 was removed and the resulting liquid was heated to 280<*>C to remove hexane by evaporation, and the obtained residue was pelletized at 250°C. The polymerization activity was 7600 g/mM.Ti. The resulting polybutene-1 resin is hereinafter referred to as "PB-A".

Reference example B

Polymerization was carried out in the same manner as in Reference Example A, except that the molar ratio of hydrogen/butene-1 was changed to 0.5, whereby a polybutene-1 resin (hereinafter referred to as "PB-B") was prepared. .

Reference example C

Polymerization was carried out in the same manner as in Reference Example A except that 20 mM/h cyclohexylmethyl-dimethoxysilane was used and the hydrogen/butene-1 ratio was changed to 0.006, thereby obtaining a polybutene-1 resin (hereinafter referred to as " PB-C").

Reference example D

Polymerization was carried out in the same manner as in Reference Example A, except that 20 mM/h cyclohexylmethyl-dimethoxysilane was used and the hydrogen/butene-1 molar ratio was changed to 1.5, whereby a polybutene-1 resin was obtained in the subsequent denoted by "PB-D".

Reference example E

Into a 200-1 SUS-made reactor was continuously fed 500 l/h hexane, 50 l/h liquid butene-1, 100 mM/h titanium trichloride (manufactured by Toho Titanium Co., Ltd., "TAC-141") , 100 mM/hr diethyl aluminum chloride, 100 mM/hr diethyl aluminum iodide and hydrogen. The hydrogen was fed in so that the molar ratio of hydrogen/butene-1 in the gas phase part of the reactor was 0.04. The polymerization temperature was kept at 60°C and the polymerization pressure was 4.8 bar. The contents were continuously withdrawn while maintaining the level in the polymerization apparatus at 100 L. 1 L/hr methanol was added to the polymerization solution, butene-1 was removed, and 100 L/hr water was added followed by stirring, the water was separated, and the residue was heated to 280°C to remove hexane by evaporation, and the residue obtained was pelletized at 250°C. The polymerization activity was 63 g/mM/Ti. The obtained polybutene-1-resin is hereinafter referred to as "PB-E".

Reference example F

Polymerization was carried out in the same manner as in Reference Example A, except that 1 mM/h cyclohexylmethyl-dimethoxysilane was used, and the hydrogen/butene-1 molar ratio was changed to 0.02, thereby obtaining a polybutene-1 resin (in which hereafter referred to as "PB-F").

Reference example G

Polymerization was carried out in the same manner as in Reference Example A, except that the molar ratio of hydrogen/butene-1 was changed to 0.02, thereby obtaining a polybutene-1 resin (hereinafter referred to as "PB-G").

Examples 1-3

The antioxidants "Irganox 1330", "Irganox 1010" and "Irganox 1076" were added respectively. amounts of 0.4 parts by weight, 0.3 parts by weight and 0.2 parts by weight to 100 parts by weight of each of the mixtures shown in Table 1 of a butene-1 homopolymer (PB-A)

(MFR: 0.2 g/10 min. (ASTM: D 1238, E), Hw/Mn = 4.5, II = 95%) and a butene-l-homopolymer (PB-B) (MFR: 20 g /10 min.

(ASTM: D 1238, E), Mw/Mn = 4.5, II = 95%). To each mixture was added 0.2 parts by weight of polyethylene as a nucleating agent, 0.05 parts by weight of an isoindolinone yellow organic pigment as a pigment and 0.2 parts by weight of titanium oxide. Then each mixture was stirred and mixed in

a "Henschel mixer", melted and kneaded using a 65 mm diameter extruder to produce pellets of polybutene-1 resin blends.

The resulting pellets were subjected to heat pressing at a temperature of 200°C for 10 min. for melting, and pressurized for 5 min. in a cooling press at approx. 30°C to produce two types of pressed sheets with a thickness of 2 mm and 3 mm. These sheets were used as a sample and examined with regard to heat resistance, yield strength in tensile tests and impact strength according to the previously mentioned methods. Furthermore, pipes were manufactured and evaluated for internal pressure resistance and castability of the pipes. The results are shown in table 1.

Example 4

Pellets of a polybutene-1 resin mixture were prepared in the same manner as in Example 2, except for the addition of ethylene bisstearoamide (EBSA) as a nucleating agent. Pressed sheets were produced from the obtained pellets and examined with regard to heat resistance, yield strength at tensile load and impact strength, and tubes were produced from the obtained pellets and evaluated with regard to internal pressure resistance and castability of the tubes. The results are shown in table 1.

Example 5

Pellets of a polybutene-1 resin mixture were prepared in the same manner as in Example 2, except that no nucleating agent was added. Pressed sheets were produced from the obtained pellets and examined with regard to heat resistance, yield strength with tensile test and impact strength, and tubes were produced from the obtained pellets and evaluated with regard to internal pressure resistance and castability of the tubes. The results are shown in table 1.

Examples 6 and 7

Pellets of a polybutene-1 resin mixture were prepared in the same manner as in Example 2, except that a butene-1 homopolymer (PB-C) (MFR: 0.05/10 min., Mw/Mn =5, II = 97%) and a butene-1-homopolymer (PB-D) MFR: 100 g/10 min., Mw/Mn = 5, II = 97%) were mixed in the proportions shown in Table 1. Pressed sheets were produced from the obtained pellets and examined with regard to heat resistance, yield strength with tensile test and impact strength, and tubes were produced from the obtained pellets and evaluated with regard to internal pressure resistance and castability of the tubes. The results are shown in table 1.

Comparative example 1

A mixture was prepared in the same manner as in Example 1 except that no butene-1-homopolymer (PB-B) was used. In the same way as in example 1, sheets were produced and examined with respect to heat resistance, yield strength with tensile test and impact strength, and tubes were produced and evaluated with respect to internal pressure resistance and castability of the tubes. The results are shown in table 2. As shown in Table 1, a remarkably rough surface was obtained on the inner and outer surfaces of the resulting pipe when the pipe was cast at a speed of 10 m/min.

Comparative example 2

A mixture was prepared in the same manner as in Example 1, except that no butene-1-homopolymer (PB-A) was used. In the same manner as in Example 1, sheets were prepared and examined for heat resistance, tensile yield strength and impact strength, and tubes were prepared and evaluated for internal pressure resistance and castability of the tubes. The results are shown in table 2. The resulting sheets had poor impact strength and with regard to pipe casting, this was impossible due to that the viscosity of the molten billet was extremely low.

Comparative example 3

A mixture was prepared in the same manner as in Example 1, except that a butene-1-homopolymer (PB-E) (MFR: 0.5 g/10 min., Mw/Mn = 12, II = 95%) was used instead of the butene-1 homopolymers (PB-A) and (PB-B). Sheets were prepared from the mixture in the same manner as in Example 1 and tested for heat resistance, tensile yield strength and impact strength, and tubes were prepared from the mixture and evaluated for internal pressure resistance and castability of the tubes. The results are shown in table 2.

Comparative example 4

A mixture was prepared in the same manner as in Example 1, except that a butene-1-homopolymer (PB-F) (MFR: 0.5 g/10 min., Mw/Mn = 4.5, II = 90%, was used in place of the butene-1 homopolymers (PB-A) and (PB-B). Sheets were prepared from the mixture in the same manner as in Example 1 and examined for heat resistance, tensile yield strength and impact strength, and tubes were prepared from the mixture and evaluated with regard to internal pressure resistance and castability of the pipe. The results are shown in table 2. The resulting sheets exhibited low yield strength under tensile test and when determining the internal pressure resistance of the pipes they burst at stresses of 75 kg/cm<2 >.Furthermore, in tube casting, remarkable rough surfaces were formed on the inner and outer surfaces of the resulting tubes.

Comparative example 5

A mixture was prepared in the same manner as in Example 1, except that a butene-1-homopolymer (PB-G) (MFR: 0.5 g/10 min., Mw/Mn = 4.5, II = 95%) was used instead of butene-l-homopolymers (PB-A) and (PB-B). Sheets were prepared from the mixture in the same manner as in Example 1, and examined for heat resistance, tensile yield strength and impact strength, and tubes were prepared of the mixture and evaluated with respect to internal pressure resistance and castability of the pipes. The results are shown in Table 2. The resin composition of the present invention is a polybutene-1 resin composition which has properties such as excellent stiffness, creep resistance and impact resistance strength, which are characteristic of a polybutene-l resin, as well as having excellent castability, especially castability at high casting speeds, so-called high-speed castability. A pipe cast from the resin mixture according to the invention is therefore a pipe which is suitable as pipe material for hot water supply and water supply in general.

Claims (9)

1. Polybutene-1 resin mixture, characterized in that it essentially comprises: (A) 60 - 95% by weight polybutene-1 resin (A) optionally including 20 mol% of a copolymerizable α-olefin with 2-20 carbon atoms, and where the resin (A) has (i) a melt flow rate (ASTM D 1238, E) of 0.01 - 5 g/10 min, (ii) a ratio (Mw/Mn) between the weight average molecular weight (Mw) and the number average molecular weight ( Mn) of 6 or less, and (iii) an isotaxity value of 93% or more, (B) 40 to 5% by weight polybutene-1 resin (B) optionally including 20 mol% of a copolymerizable α-olefin with 2-20 carbon atoms , and where the resin (B) has i) a melt flow rate 20 times or more greater than that of the polybutene-1 resin (A), ii) a ratio (Mw/Mn) between the weight average molecular weight (Mw) and the number average molecular weight ( Mn) of 6 or less, and (iii) an isotaxicity value of 93% or more, where the isotactic value of the resins (A) and (B) is measured by dissolving 1 g of the resin in 100 ml of decane, cooling the solution to 0°C, leaving the solution at 0°C for 24 hours and determining the weight % of the insoluble part in relation to all of the resin, which corresponds to the isotactic value. 2. Resin mixture according to claim 1, characterized in that it comprises 70-90% by weight of polybutene-1 resin (A) and 30-10% by weight polybutene-1-resin (B). 3. Resin mixture according to claim 1, characterized in that the polybutene-1 resin op\ (A) has a melt index of 0.1-2 g/10 min.. 4. Resin mixture according to claim 1, characterized in that the polybuteh-1 resin (A) has a Mw/Mn ratio of 5 or less. 5. Resin mixture according to claim 1, characterized in that the polybutene-1 resin (A) has an isotactic value in the range 93-98%. 6. Resin mixture according to claim 1, characterized in that the polybutene-1 resin (B) exhibits a melt flow rate 50-1,000 times greater than that of the polybutene-1 resin (A). 7. Resin mixture according to claim 1, characterized in that the polybutene-1 resin (B) exhibits a Mw/Mn ratio of 5 or less. 8. Resin mixture according to claim 1, characterized in that the polybutene-1 resin (B) has an isotacticity value of 93-98%. 9. Resin mixture according to any of the preceding claims, characterized in that it per 100 parts by weight of the resin mixture of (A) and (B) comprises 0.01-2 parts by weight of a nucleating agent, and 0-20 parts by weight of a thermoplastic polymer other than polybutene-1 resin.